Formation of dense, highly lustrous and impervious deposits of nickel



Patented Sept. 4, 1934 roam-non or DENSE, HIGHLY ws'raous nn nursnvrous nnrosrrs or mom Max Schliitter, Berlin, Germany No Drawing.

Application November 10, 1932, Serial No. 642,022

15' Claims. (Cl. 204-14) My invention relates to the formation of dense, highly lustrous and impervious deposits-of nickel and similar metals and to a process of electrodeposition of such deposits.

When nickel is deposited electrolytically from a solution of the salts heretofore used for nickel plating, a 'dull deposit is obtained which must be subsequently polished mechanically to obtain a glossy or lustrous surface. By the use of colloids of high molecular weight (about 5000 or more) in the plating baths heretofore employed, it has been possible to obtain a deposit of high lustre but the mechanical properties of the deposits thus obtained are adversely afiected. The resistance of such deposits against corrosion, cracking and peeling are reduced by the action of the colloids and the deposits are brittle and not suitable for further working.

. An object of the present invention is to provid a deposit or coating of nickel that has an inherent high gloss, high resistance to abrasion and to penetration and corrosion.

A further object is to provide a process by which a nickel deposit with a high gloss may be formed electrolytically.

v In my invention, I form a deposit in which the size of the crystals is much smaller than in any deposits heretofore obtainable and, therefore, one

in which the surface formed by the crystals is so fine grained as to produce, without mechanical polishing, an appearance of high lustre. The deposition of the metal in crystals of extreme fineness also gives a hard, compact deposit that is highly resistant to scratching, abrasion or corrosion. This glossy nickel deposit may be produced in any desired thickness up to one millimeter and over. Y

I accomplish the above deposits by electrolytic deposition in the presence oforganic colloids of much smaller molecular weights than those of colloids heretofore used, that is, of a molecular weight lessthan 5000. In the electrodeposition of the metal these colloids are deposited into the deposit by kataphoresis, adsorption or other capillary action. Heretofore, when heavy or high molecular weight colloids have been used, their size disturbed or interfered with the union of the crystals, whereas, with colloidal material of smaller molecular weight, less space is taken by the colloid and the interlacing or union of the crystals is not impaired, and adherent, fine grained or high gloss deposits may be obtained of a thickness up to a millimeter or over. 7

The material to be suitable for this purpos must dissolve in water toform a colloidal solution and be capable of being deposited by adsorption or kataphoresis in small quantities to delay the speed of growth of the crystals. The growth of the crystal is thereby retarded and smaller crystals are obtained.

The following are examples of electrolytic baths for the deposition or nickel by-my invention:

Example I An electrolytic bath is formed 01-} p v Grams Nickel sulphate 160, Nickel ben'zoldisulphonate' 30 Boric acid 30 in suincient water to give a pH value of 2.5 to 4.5.

Ewample'II v An electrolytic bath is formed of Grams Nickel chloride 160 Nickel naphthalenetrisulphonate 30 Boric acid 30 and water sufilcient to give a pH value of 2.5 to 4.5.

It will be understood that other nickel salts may be used as electrolytes and thatotlier aromatic pol'y-sulphonates may be employed and the proper acidity may be obtained by other acids than boric acid.

Deposits of nickel made by the use of the above baths have very small crystals, as small as about one ten-thousandth of a millimeter, and

The action of the colloids is,-in a sense, me-

chanical in'interfering with the building up oflarger crystals due to the electrodeposition by kataphoresis on, the deposit and thus breaking the continuity of the crystals. It will be understood, therefore, that the above examples are illustrative rather than as limiting, and that other colloids than those mentioned may be used.

'WhatIclainiist ,v v 1. A high gloss compact-and adherent deposit I or nickel having a crystal size of less than about lone ten-thousandth or a millimeter and containing a small amount of a colloidal organic nickel -salt.'

3. A metal base-having a suriace deposit of nickel, the crystal size in said deposit being less than one ten thousandth or a; millimeter.

4;",A process for the electrodeposition of nickel which comprises passing electric current from an "anode to a cathode through an electrolyte bath oi nickel in the presence in said bath or nickel ben'z::nedisulphonate.

5. A process for the electrodeposition of nickel which comprises passing. electric current from an anodeto a cathode through an electrolyte bath of nickel in the presence in said bath of nickel naphthalenetrisulphonate.

' 6. A process for the electrodeposition of nickel having a crystal sizeless than 1/10000th of a a millimeter which comprises'passing electric cur- *rent from an anode to a cathode through an electrolyte bath in the presence of an aromatic sulphonate containing more than one sulphonic acid group.

"l. A process for the electrodeposition of nickel having a'crystal size less than 1/10000th of a millimeter which comprises passing electric current from an anode to a cathode through an electrolyte bath of nickel in the presence in said bath'ot an aromatic poly-sulphonate of nickel.

8. A high gloss compact and adherent deposit of nickel having acrystal size of less than about 1/l0000th oi. a millimeter and a thickness substantially greater than 1/10000th of a millimeter.

9. A process for the electrodepositionof nickel which comprises "passing an electric current from an anode to a cathode through an electrolytic bath of nickel in the presence in said bath 01 a benzene sulphonate containing more than one and less than four sulphonic acid groups.

10-. A process for the electrodeposition of nickel whichcomprises passing electric current from an anode to a cathode throughan electrolyte bath 0! nickel in the presence in said bath of naph thalene sulphonate containing'more than one and less than four sulphonic acid groups.

11. A process for the electrodeposition of nickel which comprises passing electric current from an anode to a cathode through an electrolyte bath in the presence 01' an aromatic suiphonate containing more than one and less than tour sulphonic acid groups and containing a chloride.

12. A process for the electrodeposition oi'nickel which comprises passing electric-current from an anode to a cathode through an electrolyte hath in the presence in said bath of a nickel aromatic poly-sulphonat'e of less than four sulphonic acid groups and containing a chloride.

13. A process for'the electrodeposition of nickel which comprises passing electric current from an anode to a cathode through an electrolyte bath in the presence in said bath of a nickel aromatic poly-sulphonate of less than four sulphonic acid groups.

14. A process for the electrodeposition of nickel having a crystal sizeless than 1/10000th of a millimeter which comprises passing electric cur- MAX sermon-ER. 

